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ASR is a reaction between the alkali hydroxides in concrete and reactive forms of silica in the aggregate. The reaction forms a gel that swells when moisture is present. The two step process can be visualized as: 1. Alkali + Silica → Gel reaction Product 2. Gel reaction Product + Moisture → Expansion Factors Affecting ASR
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The first stage of the alkali-silica reaction is the reaction between the hydroxyl ions (OH −) in the pore solution and reactive silica in the aggregate; the silica is not directly attacked by the alkali metal cations (Na + and K +).The alkalis contribute initially to the high concentration of hydroxyl ions in solution and later to the formation of an expansive alkali-silica gel.
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ASR is the chemical reaction between the alkali in the cement, the silica in the aggregate and the presence of water. When ASR occurs in a concentrated concrete product, issues such as cracking, deformation and weakening of joints have been found, thus putting into question the structural integrity and lifespan of roads and bridges.
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The influence of low CaO steel slag, calcined clay and granite dust on the alkali-silica reaction was investigated over a period of 35 days under accelerated curing conditions. The mineral admixtures were used to replace ... granite quarry near Kumasi. Class 32.5R Portland limestone cement (PLC) manufacturedby Ghana Cement Company Limited ...
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Katayama suggested that alkali–silica reaction (ASR) had a role in the alkali–carbonate reaction (ACR). At the time, our Canadian colleagues thought that the result obtained by Katayama was anomalous and that ACR was a separate type of reaction. ... Due to the great variability in the petrology and reactivity of the Pittsburgh quarry top ...
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Recycling of quarry dust for supplementary cementitious materials in low carbon cement. ... Relatively slow reaction rate is commonly found in the alkali activated materials when using less-basic activators, such as CaO [37], ... although no reaction of silica fume was found to react by 29 Si NMR ...
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Mitigation of Alkali-Silica Reaction in Volcanic Aggregate CONCRETE USING PFA AND GGBS Annual Concrete Seminar 2016 (20 April 2016) Ryan C. Y. Chi, Engineer 2 / Laboratory 2 Public Works Central Laboratory Standards & Testing Division, ...
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1. Introduction. The aggregates which are potential alkali silica reactive may cause a severe degradation of concrete structure due to external environmental factors such as high humidity and sea saline water [1].When concrete is affected by alkali silica reaction (ASR), map like cracks are developed and durability of concrete is reduced [2].As stated by Fatt and Beng …
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The compressive strength of the 30% bagasse ash-20% quarry dust based heat cured alkali activated specimens is decreased 35.1% compared to the control specimens. …
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ASR is a reaction between the alkali hydroxides in concrete and reactive forms of silica in the aggregate. The reaction forms a gel that swells when moisture is present. The two step …
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The inclusion of quarry dust in cement bound materials and its effect on various properties of cement such as transport, dimensional stability, alkali-silica reaction, the heat of hydration and ...
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ASR is a reaction between the alkali hydroxides in concrete and reactive forms of silica in the aggregate. The reaction forms a gel that swells when moisture is present.
WhatsApp: +86 18221755073
It was calculated an equivalent alkali (Na2Oäq) in CBPD was up to19% that may increase the alkali-silica reaction (ASR) damage in concrete when an aggregate rich in reactive silica is used.
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Alkali-silica reaction (ASR) and its associated deformation are major durability problems in concrete structures and was reported as far back as the 1940s by Stanton (2008) [1].
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This study presents the contribution of petrography to the comprehension of the alkali-silica reaction mechanism applied to two siliceous limestones. ... aggregates The two siliceous limestone aggregates have been extracted from two different exploitation floors of a quarry from the North of Europe. Each floor is about 15 m height and is ...
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mitigate alkali-silica reaction, a common problem in concrete that leads to cracking and deterioration. Combining quarry dust and fly ash in concrete can lead to synergistic effects. …
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There are a number of ASTM tests used to identify alkali-silica reactive aggregates, and the effects of different alkali-bearing cements and pozzolans in accommodating the ASR reaction. Nevertheless, in many areas …
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ASR is a reaction between the alkali hydroxides in concrete and reactive forms of silica in the aggregate. The reaction forms a gel that swells when moisture is present. The two step process can be visualized as: 1. Alkali + Silica → Gel reaction Product. 2. Gel reaction Product + Moisture → Expansion. Factors Affecting ASR
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Engineering Solid Mechanics, 2018. This study synthesizes the use of chemicals to prevent one of common concrete durability problems, alkali-silica reaction (ASR), and can help researchers (i) identify widely used potential chemicals and evaluate these chemical solutions to prevent ASR with proper understanding of mechanisms, and (ii) to identify the research gaps in order to …
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The use of fly ash in concrete is desirable because of benefits such as useful disposal of a byproduct, increased workability, reduction of cement consumption, increased sulfate resistance, increased resistance to alkali-silica reaction and decreased permeability. However, the use of fly ash leads to a reduction in early strength of concrete. The use of quarry dust in concrete is …
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The objective of this study is to develop a new generation of alkali-silica reaction (ASR) inhibiting powder additives or liquid chemical admixtures for concrete. Throughout the paper, the word additive primarily refers to a powder while admixture primarily refers to liquid (pre-dissolved powder); otherwise, the two terms are used interchangeably.
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replacement for strength and durability testing, for alkali-silica reaction expansion (ASR) and chloride attack. From the analysis it is found that there is marginal workability and strength loss for up to 10% cement replacement. ... Granite quarry dust from a local crusher unit is collected for the study. The sludge obtained from washing the ...
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Alkali-silica reaction (ASR) is a deleterious chemical reaction that can occur in concrete between aggregates containing reactive silica and the alkaline pore solution present within the matrix of concrete. The ... value of 0.35%, from Adairsville Quarry in …
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In the last few decades, the alkali–silica reaction (ASR) has been reported as one of the major concrete concerns regarding durability, leading to high maintenance and reconstruction costs. The occurrence of ASR in numerous concrete infrastructures all over the world points to the need for research regarding measures for its detection in an ...
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There are several procedures to mitigate alkali–silica reaction: (a) the use of supplementary cementitious materials (e.g., ground granulated blast furnace slags and fly …
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Alkali-Silica reactions occur over time between alkaline cement paste and silica contained in rock aggregates as a result of the swelling due to the reaction of certain constituents in the rock ...
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Higher levels of reactive silica in aggregates can be detrimental to concrete if it reacts with the alkaline cement paste. Many aggregates, especially the surface aggregates used in Tennessee, have a relatively high siliceous content (e.g., gravels, siliceous limestones, granites, and quartzite). Aggregates with Alkali Silica Reaction (ASR)
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One of the pathological phenomena occurring in silica-rich rocks is the AAR alkali–aggregate reaction and is addressed in this article given the strong evidence of the damaging capacity of …
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Stone dust or quarry dust is a byproduct of crushing stone for use in construction. It is composed of finely crushed stone particles that are angular in shape. ... Stone dust may contain reactive minerals that can react with the …
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The bulk generation of quarry dust (QD) from quarries, aggregates, and decorative stone plants, is a serious environmental issue. However, QD has the potential to provide eco-economic and technical merits when incorporated in the construction products. ... gas permeability, alkali-silica reaction (ASR), water penetration depth corrosion, and ...
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Identification of alkali-silica reaction. Gel may be present in cracks and within aggregate particles. The best technique for the identification of ASR is the examination of concrete in thin section, using a petrographic microscope. Alternatively, polished sections of concrete can be examined by scanning electron microscopy (SEM); this has the ...
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This study explored the effect of adding 10% or 20% granite quarry dust to cement on properties such as transport (total and capillary water absorption and electrical resistivity), dimensional stability (drying shrinkage and expansion), the alkali-silica reaction, heat of hydration and colour. No alkali-silica reaction was observed in the new ...
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Alkali-silica reaction is a chemical phenomenon which can occur in field concrete and is readily reproduced on demand in laboratory investigations. Visible or measurable distress arises as a …
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According to Ho et al. [6] in normal concrete, the introduction of quarry dust to mixes must be limited due to its high fineness. Its addition to fresh concrete would increase the water demand and consequently the cement content for given workability and strength requirements. ... Alkali–silica reaction (ASR) of mortar containing this waste ...
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alkali-silica reaction in the material can be achieved by adding 10 to 40 percent rice husk ash to cement. Abubakr (2019) partially substituted recycled ceramic powder for cement in standard concrete specimens. Based on their research, flexural strength, density, and workability are all improved when there is a 10-20% fine ceramic powder
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Ash and Quarry Dust Chaturanga Lakshani Kapugamage, Garisson Engineer, Sri Lanka Army (e-mail: chatushani@yahoo) ... resistance to alkali-silica reaction and decreased permeability. However, the use of fly ash leads to a reduction in early strength of concrete. The use of quarry dust in concrete is desirable because of
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